JPS63291969A - Repeelable tackifying agent - Google Patents

Abstract

PURPOSE:To obtain the titled tackifying agent with good repeelability, suitable for application on surface-protecting members, etc., by incorporating a non- silicone tackifying agent with a monomer having affinity for said agent and a specific silicone graft copolymer. CONSTITUTION:The objective tackifying agent can be obtained by incorporating (A) a non-silicone tackifying agent (e.g., acrylic one), with (B) a monomer having affinity for the component A and (C) a silicone graft copolymer constituted by silicone macromonomer [e.g., of formula I, II (R is H or methyl), etc.]. The content of the component C is pref. such as to be 0.05-21wt.% on a silicone macromonomer unit basis.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a non-silicone adhesive containing a silicone graft copolymer and having good removability and suitable for surface protection materials and the like.

Conventional techniques and problems Conventionally, phosphate ester or amine surfactants are added to adhesives to suppress the increase in adhesive strength to the adherend over time, thereby making re-peeling from the adherend easier. Adhesives that were easy to use were known.

In addition, in the method of blending the surfactant into the adhesive, the release properties tend to vary, so in order for the surfactant to occupy the surface of the adhesive layer, it is necessary to add a surfactant to the back side of the support base material. There is also a known one provided with an agent layer (Japanese Unexamined Patent Publication No. 55-38841).

However, in any of the above methods, there is a problem in that the surface of the adherend is contaminated with the surfactant.

Means for Solving the Problems The inventors of the present invention have conducted extensive research to develop a removable adhesive that is less likely to cause such contamination problems, and as a result, the inventors have found that they contain a special silicone-based graft copolymer. The inventors have discovered how to achieve the object and have come up with the present invention.

That is, the present invention provides a removable adhesive characterized in that a non-silicone adhesive contains a silicone graft copolymer containing a monomer having affinity with the adhesive and a silicone macromonomer. It provides:

Function The silicone-based graft copolymer described above is easily separated from the adhesive and has an excellent effect of suppressing an increase in adhesive strength. This is because the silicone macromonomer has excellent compatibility or bonding strength with the adhesive based on the affinity monomer component, but on the other hand, the silicone macromonomer is more likely to be alienated than the adhesive, and therefore the copolymer on the surface of the adhesive layer This seems to be because the silicone macromonomer component tends to be located on the surface of the adhesive layer.

Examples of Components of the Invention The adhesive used in the present invention is non-silicone. That is, it is an adhesive other than a silicone adhesive, such as an acrylic adhesive or a rubber adhesive. It may contain a compounding agent such as a curing agent that does not cause contamination of the surface of the adherend. From the viewpoint of weather resistance, an acrylic pressure-sensitive adhesive whose base polymer is a polymer containing 50% by weight or more of an ester such as acrylic acid or methacrylic acid, especially a neutral ester, is preferable.

The silicone-based graft copolymer used in the present invention contains a monomer having an affinity for the adhesive containing the copolymer, and a silicone macromonomer as constituent components.

The affinity monomer is appropriately determined depending on the adhesive used. Generally, monomers constituting the adhesive and monomers having excellent compatibility with the monomers are used. Typical examples thereof include esters such as acrylic acid and methacrylic acid, styrene and its derivatives, acrylic acid, methacrylic acid, vinyl acetate, and acrylonitrile.

On the other hand, silicone macromonomers are typically 1.00% silicone macromonomer with a relatively low molecular weight and having a polymerizable functional group at the end of the molecular chain.
Those having a weight average molecular weight of about 0 to 20,000 are used. Typical examples include those represented by the following general formula.

CH CH.

CHz=CRCoo-C9H65i(O8i(CHi)
shCH2=CR-Coo-CsHa-8i-+o-X
)? (However, R in the above formula is hydrogen or a methyl group, and X is (Si(CH%-〇+T-8i(CH)). The methyl group may be an ethyl group or a phenyl group, and the methoxy group may be an ethoxy group (although the present invention is not limited to the above).

The silicone-based graft copolymer can be prepared, for example, by reacting the affinity monomer with a silicone macromonomer using a conventional solution polymerization method, emulsion polymerization method, suspension polymerization method, bulk polymerization method, etc. . In addition, as a preparation method, a solution polymerization method is preferable from the viewpoint of simplicity.

There is no particular limitation on the method of incorporating the silicone-based graft copolymer into the adhesive of the present invention, and methods include mixing separately prepared products, or adding a silicone macromonomer at the time of preparing the non-silicone-based adhesive. A common method is to prepare a silicone-based graft copolymer at the same time as the adhesive.

The content of the silicone-based graft copolymer is 0.05 to 2 silicone macromonomer units in the adhesive (solid content).
An amount of 0% by weight is appropriate, and an amount of 0.1 to 10% by weight is particularly preferred. If the content of the silicone macromonomer unit is less than 0.05% by weight, the addition effect will be poor and satisfactory removability will not be achieved;
If it exceeds 100%, adhesion to supporting substrates etc. becomes poor and contamination of adherends tends to occur.

The adhesive of the present invention can be easily re-peeled. Therefore, it is preferably used for materials that need to be re-peeled once attached to an adherend, such as surface protection materials or masking materials intended to prevent damage during processing or transportation. In that case, the adhesive is generally used in a state attached to a suitable support base material such as paper thread, heathered thread, plastic type, metal foil type, etc. Examples of adherends to which the adhesive is attached include metal plates, plastic plates, glass plates, silicon plates, and semiconductor boards. The adhesive can be easily attached to the adherend by a conventional method such as a roll pressure bonding method.

Effects of the Invention The adhesive of the present invention has excellent removability because it contains a silicone type and a graft copolymer. In addition, since the silicone-based kraft copolymer contains a monomer that has an affinity with the adhesive, it is easily separated from the adhesive, and therefore has excellent non-staining properties for adherends.

Examples Reference Example 1 (Adhesive) 75 parts of butyl acrylate (parts by weight, the same applies hereinafter), 20 parts of butyl methacrylate, and 5 parts of 2-hydroxyethyl methacrylate were mixed in toluene with 0.5 part of benzoyl peroxide. A toluene solution of the acrylic pressure-sensitive adhesive was obtained by copolymerization treatment at 70° C. for 24 hours.

Reference Example 2 (Silicone-based graft copolymer) CH.

30 parts of silicone macromonomer represented by 2. 50 parts of butyl acrylate, and 20 parts of butyl methacrylate.
After polymerization in toluene at 70°C for 16 hours in the presence of 1 part of 2'-azobisisobutyronitrile, toluene was distilled off from the reaction solution under reduced pressure to obtain a weight average molecular weight of 150.000.
A silicone-based graft copolymer was obtained.

50 parts of silicone macromonomer represented by Reference Example 3 (silicone-based graft copolymer) and 50 parts of styrene were mixed into 2
, 2'-azobisisobutyronitrile in the presence of 1 part in toluene at 80°C for 20 hours, toluene was distilled off from the reaction solution under reduced pressure to obtain a weight average molecular weight of 80.00.
Example 1 in which a silicone-based graft copolymer of No. 0 was obtained. 97 parts (solid content, same hereinafter) of the acrylic adhesive of Reference Example 1, 1 part of the silicone-based graft copolymer of Reference Example 2, and a polyisocyanate-based Two parts of crosslinking agent were mixed to obtain an adhesive solution. The content (calculated value) of silicone macromonomer in the adhesive is 0.3% by weight.

Example 2 88 parts of the acrylic pressure-sensitive adhesive of Reference Example 1, 10 parts of the silicone-based graft copolymer of Reference Example 2, and 2 parts of the polyisocyanate-based crosslinking agent were mixed to obtain a pressure-sensitive adhesive solution. Note that the content (calculated value) of silicone macromonomer in the adhesive is 3.0% by weight.

Example 3 68 parts of the acrylic pressure-sensitive adhesive of Reference Example 1, 30 parts of the silicone-based graft copolymer of Reference Example 2, and 2 parts of the polyisocyanate-based crosslinking agent were mixed to obtain a pressure-sensitive adhesive solution. Note that the content (calculated value) of silicone macromonomer in the adhesive is 8.9% by weight.

Example 4 72 parts of butyl acrylate, 20 parts of butyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, and 3 parts of the silicone macromonomer used in Reference Example 2 were mixed with 0.5 part of benzoyl peroxide in toluene. A toluene solution of an acrylic adhesive was obtained by copolymerization at 70°C for 24 hours in the presence of the adhesive, and 2 parts of a polyisocyanate crosslinking agent was mixed with 98 parts (solid content) of this adhesive to form an adhesive solution. Obtained. The content of silicone macromonomer in the adhesive (calculated value) is 3.0% by weight.

Example 5 80 parts of a styrene-butadiene-styrene rubber pressure-sensitive adhesive having a weight average molecular weight of too and ooo and a styrene content of 30% by weight was mixed with 20 parts of the silicone-based graft copolymer obtained in Reference Example 3. An adhesive solution was obtained. Note that the content (calculated value) of silicone macromonomer in the adhesive is 9.9% by weight.

Comparative Example 1 A pressure-sensitive adhesive solution was obtained according to Example 1, using 98 parts of the acrylic pressure-sensitive adhesive of Reference Example 1 and 2 parts of the polyisocyanate-based crosslinking agent, but not using the silicone-based graft copolymer.

Comparative Example 2 An adhesive solution was obtained according to Example 1, except that the amount of the acrylic adhesive used was 18 parts and the amount of the silicone graft copolymer was changed to 80 parts. The content of silicone macromonomer in the adhesive (calculated value) is 23.8% by weight.
It is.

Comparative Example 3 The styrene-butadiene-styrene rubber adhesive used in Example 5 was used as is.

The adhesive solutions obtained in the evaluation test examples and comparative examples were applied onto a polyester film with a thickness of 25 parts m so that the thickness after drying was 20 μm, and the adhesive solution was dried at 100°C for 5 minutes to obtain adhesive. A tape was prepared and subjected to the following test.

1 Adhesive strength J At 20℃, 65% RH, ST plate (stainless steel plate 5US
304) was pressed with a 2 kg roller once and left for 20 minutes, and the 180 degree peeling adhesive strength of the adhesive tape was measured using an Instron type universal testing machine at a tensile speed of 300 min/min (20°C, 65%RH)t.

[Removability 1: Press the adhesive tape as described above at 35°C x 85% RH.
, 50℃ x 65% old 1.50℃ x 90%RH or 70℃
After being left in an atmosphere of 65% RH for 72 hours, the adhesive strength was measured in the same manner as described above.

[Non-contamination] Visually observe the surface of the stainless steel plate after examining removability.
0 if the same as before applying the adhesive tape; △ if clouding was observed; × if glue (adhesive) residue was observed.
It was evaluated as

The results are shown in the table.

In addition, the units for adhesive strength and removability in the table are g/20
− is.

Claims (1)

[Scope of Claims] 1. A removable type characterized in that a non-silicone adhesive contains a silicone graft copolymer containing a monomer having affinity with the adhesive and a silicone macromonomer. adhesive. 2. The adhesive according to claim 1, wherein the content of the silicone-based graft copolymer is 0.05 to 20% by weight based on silicone macromonomer units. 3. The adhesive according to claim 1, wherein the non-silicone adhesive is an acrylic adhesive.